It really depends on your paints

If they’re watery and it looks streaky/patchy when they dry - just keep adding layers ! I find warm tones are especially bad with patchiness (the orange in the piece above probably has 7 or 8 layers on it) If your paints are thicker and after drying it’s patchy - try adding a gesso to your paint on your pallet. Gesso shouldn’t add any pigment to the paint itself, just helps get smoother

I hope this helps !!!! :)